1. Field of the Invention
This invention relates to structures and methods for fabricating thin film perpendicular write heads. More specifically, the invention relates to structures and methods for fabricating wrap around and trailing shields using ultra-thin metal gap seed layers.
2. Description of the Related Art
Perpendicular write heads are currently well known in the art. Variants of such heads, having wrap around shields and trailing shields, have been recently disclosed. See, for example US Patent Application Publications 2005/0259355, 2006/0044682 and 2006/0174474, assigned to Hitachi Global Storage Technologies, Netherlands B.V.
During the fabrication of the wrap around shield of the prior art, a film stack containing the magnetic pole material, a non-magnetic gap layer, a CMP stop layer, and a number of image transfer layers are deposited. After the pole width is imaged and the film stack etched by a number of consecutive etch processes, a film stack containing the tapered pole material is created. A conformal non-magnetic layer is then deposited, which will serve as the side shield or wrap around shield gap material. Following deposition of the side gap material, a layer of RI-etch-able (or RIE-able, reactive ion etch-able) material is deposited and the structure planarized by CMP. Following planarization, the RI-etch-able material is removed leaving the tapered pole, main gap and side gap materials. A magnetic material is then deposited over this structure by electroplating to form the wrap around shield. Prior to plating, a conductive seed layer is deposited to provide a starting cathode for the plating process. As the main gap (or top gap) continues to shrink in thickness to dimensions of a few nanometers or less, the main gap layer is eliminated from the starting film stack, being replaced by the metallic, non-magnetic seed layer used to plate the wrap around shield. Difficulties arise when trying to plate on these ultra-thin seed layers due to their higher resistivity if plating dimensions exceed a few hundred microns. In structures of the prior art, the plating of all shield structures on a wafer is done from a single blanket seed layer. This is no longer possible for seed layers having a thickness of one to two nanometers and below.
During the formation of trailing shields of the prior art, a film stack containing the magnetic pole material, a non-magnetic gap layer, a CMP stop layer, and a number of image transfer layers are deposited. The pole width is imaged and the film stack etched by a number of consecutive etch processes, creating a film stack containing the tapered pole material. A filler layer is deposited and the resulting structure planarized by CMP to the stop layer. A plating seed layer is subsequently deposited, followed by deposition of the trailing shield. As with wrap around shields, thinner gap layers require substitution of the pre-deposited gap layer in the film stack with the ultra-thin non-magnetic seed layer. Plating of the trailing shields will experience the same difficulties described above for the wrap around shields.
What is needed is a better process for producing the wrap around and trailing shields for the perpendicular write head.